1. Technical Field
Embodiments of the present disclosure relate to a semiconductor system including a semiconductor device which performs a training operation.
2. Related Art
In general, an integrated circuit including a semiconductor device includes a semiconductor system which receives an external signal inputted from an exterior and generates an internal signal. The external signal includes data, a data strobe signal, a command, an address, and/or so forth. The semiconductor system compares the external signal with a reference voltage, and generates the internal signal to be used in an internal circuit. The internal signal has a logic level according to a result of comparing the external signal and the reference voltage. For example, the logic level of the internal signal may be set to a logic high level if the external signal has a level higher than the reference voltage and to a logic low level if the external signal has a level lower than the reference voltage. The reference voltage inputted to the semiconductor system should be set to a level between a predetermined maximum level (VILmax) and a minimum level (VILmin). However, the level of the reference voltage may vary excessively due to the surroundings of the semiconductor system, the power noise of the semiconductor system, the wiring pattern of a PCB (printed circuit board), and the wiring pattern of a package. If the level of the reference voltage varies excessively, the semiconductor system may not properly determine the logic level of an external signal which is input to semiconductor device. Therefore, it is important to set the voltage level of the reference voltage so that the logic level of the external signal may be determined.